Magnetic switch contact assembly



g- 23, 1965 s. HJERTSTRAND 3,268,840

MAGNETIC SWITCH CONTACT ASSEMBLY Filed July 12, 1963 FIG, 2

Inventor $.L. HJERTSTRAND y y rney United States Patent 3,268,840MAGNETIC SWITCH CONTACT ASSEMBLY Svante Lennart Hjertstrand,.H'agersten,Sweden, assignor to International Standard Electric Corporation, NewYork, N.Y., a corporation of Delaware Filed July 12, 1963, Ser. No.294,516 Claims priority, application Sweden, July 20, 1962', 8,082/ 62 5Claims. (Cl. 335196) This invention relates in general to crossbarswitchces and in particular to an improved contact assembly suitable foruse in crossbar switches in which each contact set is selectivelyoperable in response to the establishment of a magnetic attractionbetween the intersecting horizontal and vertical rows of contactmultiples. This invention is an improvement on the crossbar switchdisclosed in my copending U.S. patent application, Serial No. 167,506,filed January 22, 1962 and entitled Magnetic Crossbar Switch, now PatentNumber 3,099,727.

In the noted application, a crossbar switch is provided in which theusual hold and select magnets and associated hold and select bars arereplaced by magnetic elements extending co-axi-ally along flexiblehorizontal and vertical multiples. At each intersection of the notedmultiples, one or more normally open contact plugs or contact points aresecured to one or both multiples. Electrical contact is establishedbetween two intersecting multiples when the magnetic elements thereonare magnetized since the multiples fiex sutficiently to bring thecontact plugs into contact with the adjacent multiple.

In certain application, such as electronic switching systems, the largeamount of operating current necessary to operate the switch of the notedapplication rendered the use of such switches prohibitive. The reasonfor these large current requirements was due to the strength of themagnetic field necessary to flex the multiples to establish the notedelectrical contact therebetween.

Accordingly, it is an object of the present invention to provide amagnetically operated contact assembly requiring a minimum of operatingcurrent.

It is another object to provide a contact assembly suitable for use incrossbar switches in which the horizontal and vertical multiples areimmovable and thus may be fabricated from material less expensive thanthe flexible material used in known switches.

In carrying out the above objects, a contact plug made from magneticmaterial is loosely mounted between the intersecting multiples andarranged to move independently of the multiples when the multiples aremagnetically energized.

Another object is to provide a contact assembly of the foregoingcharacter in which the contact plugs comprise permanent magnets whichhave insuflicient flux to actuate the contacts but when aided by thenoted magnetic energization of the associated multiples provideafast-acting switch.

Other objects and features relate to the provision of a suificientlylarge housing for the contact plugs to permit them to execute a rotatingmovement when magnetized to establish electrical connection.

Still further objects and features will become apparent and theinvention will be best understood when the specification is read inconjunction with the accompanying drawings comprising FIG. 1 and 2 inwhich:

FIG. 1 shows two contact assemblies together with .a portion of thewell-known intersecting horizontal and vertical contact multiplesmodified according to the invention; and

FIG. 2 shows one contact set having the contact plugs or points inoperated condition and the other set in unoperated condition.

3,258,840 Patented August 23, 1966 Ice Referring now to FIG. 1 of thedrawings, a description of the invention will be given.

The switch section illustrated comprises a horizontal contact multiplestrip 1 and a pair of vertical contact multiple strips 2 and 11. Thesemultiple strips may be made of a flexible or rigid magnetic materialwhich has good electrical conductivity. The multiple strips are arrangedin horizontal and vertical rows with the horizontal and vertical stripsbeing located in adjacent parallel planes. An operating conductor 5 isassociated with multiple 1 and similar operating conductors such as 6and 12 are associated with corresponding multiples 2 and 11. Aninsulating strip 7 is positioned along the horizontal multiple 1 betweenthe magnetic elements of the horizontal and vertical multiples. Thisinsulating strip could be positioned along the vertical multiples 2 and11. In either case, this insulating strip includes a plurality of[apertures 13 located at the intersection of the horizontal and verticalmultiples.

The noted apertures are of a diameter suflicient to loosely retain thecontact plugs or points positioned between associated horizontal andvertical intersecting multiples. As seen most clearly in FIG. 2, theplugs may be small cylindrical elements of a length insufficient toestablish electrical contact between adjacent multiples when the contactassembly is not energized, but sufficiently long to touch both multipleswhen tilted or rotated as shown in FIG. 2.

When multiple strips such as 1 and 2 are simultaneously magnetized, asby magnetic fields produced by current flowing through operatingconductors 5 and 6 or by magnetic fields induced in the operatingconductors by associated coil means such as C1 and C2, the contact plugs3 and 4 are attracted thereto resulting in a rotating movement whichcauses the ends of the plugs to establish electrical contact with onehorizontal multiple such as 1 and one vertical multiple such as 2.Additional coils such as C3 and C4 can be used at various cross-overpoints.

When the magnetic elements are de-magnetized, the contact plugs returnedto their normal position such as is shown in FIG. 2 for contact plugs 9and 10.

The contacting surfaces of the contact plugs may be covered with aprecious metal in order to achieve good contact properties and contactpressures.

In order to enhance the speed of operation of the contact assembly, thecontact plugs may be permanently magnetized. The degree of magnetismmust be sufliciently small to preclude operation and permit restorationof the contact assembly when the magnetic elements such as 5 and 6 arede-magnetized.

While the contact assembly has been disclosed as embodied in a crossbarswitch structure, it is to be understood that such assembly could befully utilized in individual contact stackups.

While I have described above the principles of my invention inconnection with specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationto the scope of the invention.

I claim:

1. A contact assembly comprising first and second contact strips lying aselected distance apart in separate parallel planes with the contactstrip in one plane positioned normal to the contact strip in the othersaid plane, contact means positioned between the contact strips of saidplanes at the crossover point of the first and second contact strips,said contact means being made of conductive material and formed to havea length insufficient in a normal position to bridge the selecteddistance between the first and second contact strips, a selectivelyenergizable operating conductor extending longitudinally of each of saidcontact strips for generating a magnetic field therealong, thesimultaneous generation of a magnetic field in both of said operatingconductors imparting rotational movement to said contact means to turnit from its normal position to enable it to bridge the selected distanceand to establish electrical contact between the contact strips at thesaid crossover point.

2. In a contact assembly as set forth in claim 1 mounting meanspositioned between the said operating conductors at said crossover pointfor loosely supporting said contact means in said position between saidcontact strips for free rotational movement to establish the saidelectrical contact.

3. A contact assembly as set forth in claim 1, wherein said contactmeans are comprised of magnetic material.

said contact means comprise a permanent magnet.

5. A contact assembly as set forth in claim 4 wherein the magnetic fluxof said permanent magnet contact means is insuflicient to cause movementthereof in the absence of said magnetic field in both of said strips.

References Cited by the Examiner UNITED STATES PATENTS 2,595,769 5/1952Cooley ZOO-87 3,099,727 7/ 1963 Hjertstrand 200-87 10 3,226,604 12/1965Dreyfus-Alain 317-137 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

B. DOBECK, Assistant Examiner.

1. A CONTACT ASSEMBLY COMPRISING FIRST AND SECOND CONTACT STRIPS LYING ASELECTED DISTANCE APART IN SEPARATE PARALLEL PLANES WITH THE CONTACTSTRIP IN ONE PLANE POSITIONED NORMAL TO THE CONTACT STRIP IN THE OTHERSAID PLANE, CONTACT MEANS POSITIONED BETWEEN THE CONTACT STRIPS OF SAIDPLANES AT THE CROSSOVER POINT OF THE FIRST AND SECOND CONTACT STRIPSSAID CONTACT MEANS BEING MADE A CONDUCTIVE MATERIAL AND FORMED TO HAVE ALENGTH INSUFFICIENT IN A NORMAL POSITION TO BRIDGE THE SELECTED DISTANCEBETWEEN THE FIRST AND SECOND CONTACT STRIPS, A SELECTIVELY ENERGIZABLEOPERATING CONDUCTOR EXTENDING LONGITUDINALLY OF EACH OF SAID CONTACTSTRIPS FOR GENERATING A MAGNETIC FIELD THEREALONG, THE SIMULTANEOUSGENERATION OF A MAGNETIC FIELD IN BOTH OF SAID OPERATING CONDUCTORSIMPARTING ROTATIONAL MOVEMENT TO SAID CONTACT MEANS TO TURN IT FROM ITSNORMAL POSITION TO ENABLE IT TO BRIDGE THE SELECTED DISTANCE AND TOESTABLISH ELECTRICAL CONTACT BETWEEN THE CONTACT STRIPS AT THE SAIDCROSSOVER POINT.